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The generation and isolation of two novel borenium cations has been described. The observation that the reaction of the Lewis acid B(C6F5)3 and the Lewis base diazabicyclo[2.2.2]octane (DABCO) with pinacol borane (HBpin) resulted in the activation of the B–H bond of HBpin and formation of a stable borenium cation/borohydride salt. This stable salt was used as a catalyst in the hydroboration reaction. It was shown to catalytically reduce a wide array of substrates including imines, N-heterocycles, nitriles, and ketones using pinacol borane as the source of hydride. Another borenium ion, synthesized from trityl tetrakis-pentafluorophenyl borate, DABCO, and HBpin did not contain a nucleophilic borohydride counterion and it was isolated in the solid state. This salt was also found to reduce the same substrates with similar yields and reaction times. The mechanisms of both of these catalysts were investigated and were found to be proceeding by a similar borenium catalyzed process. Quantitative analysis of the initial rates of each catalyst under identical conditions yielded rate constants on the same order of magnitude which strongly suggested that both catalysts operated via similar mechanisms. Stoichiometric experiments and isotope labelling using deuterated pinacol borane demonstrated that the nucleophilic counterion was not a kinetically relevant reducing agent under the reaction conditions. Furthermore, these reactions and the use of an isolable iminium ion as a hydride acceptor indicated that the hydride delivery agent was a DABCO•HBpin adduct. The DABCO•HBpin adduct was observed spectroscopically at ambient and subzero temperatures. Lastly, the rate of reduction using pinacol borane and [d1]-pinacol borane were significantly different and produced a high kinetic isotope effect (KIE = kH/kD = 6.6 ± 0.2). This high KIE strongly indicates that hydride delivery is the rate limiting step in the catalytic cycle. With this knowledge an asymmetric model is discussed and the beginnings of the development of an asymmetric borenium cation catalyzed process are described. / Thesis (Master, Chemistry) -- Queen's University, 2012-10-13 08:48:37.506

A catalytic organometallic addition-ring opening sequence of cyclopropenes that enables the efficient and highly stereoselective synthesis of multisubstituted alkenes has been developed. A possible mechanism of organoaluminium reaction is proposed. The metalloenolate resulting from ring opening can be trapped with various electrophiles, enabling a rapid increase in molecular complexity in a one-pot operation. Also, in the presence of stoichiometric magnesium halides, a range of bis-activated cyclopropenes undergo highly stereoselective ring-opening reactions to produce multisubstituted alkenyl halides. The halogen nucleophile promotes Lewis-acid mediated regioselective SNVσ attack at the sp2-carbon of cyclopropene, resulting in the formation of acyclic conjugate enolate, which can be trapped with enones to furnish more highly functionalised products. At last, copper-catalysed asymmetric conjugate reductions of β,β'-disubstituted 2-alkenylheteroarenes are reported. A range of nitrogen-containing aromatic heterocycles are able to provide effective activation of an adjacent alkene for highly enantioselective catalytic conjugate reduction reactions. Extension of the general concept to other classes of heteroarenes has been proven successful. Further manipulation of the condition is required to tolerate more hindered heteroarene substrates.

The problem with which this investigation was concerned was that of determining the effectiveness of massed group desensitization in the reduction of anxiety. Thirty test-anxious nursing students who scored in the upper quartile on the Test Anxiety Questionnaire (TAQ) served as the subjects. The subjects were assigned by the use of a randomized block procedure to one of the following three groups matched on the basis of their pre-test TAQ scores: (1) desensitization, (2) placebo, and (3) control.

Student Number : 0314958W - MSc dissertation - School of Process and Materials Engineering - Faculty of Engineering and the Built Environment / Microstructural characterisation was performed on Al-Ti-B grain refiners of different compositions prepared by aluminothermic reduction of TiO2 and B2O3 and dilution of the products in aluminium melts. The microstructure of the grain refiners showed needle-like TiAl3 particles as well as prismatic TiB2 particles. The TiB2 particles were coarser than those in conventional Al-Ti- B grain refiners. The microstructure also showed silicon particles and, in some cases, titanium carbide particles (TiC). The experimental grain refiners were subjected to rolling and reduced in thickness by 20, 40, 60 and 80%. The rolled samples were then heated at 625°C for 4 hours and allowed to cool slowly in the furnace. Significant changes in microstructure were noticed at 80% reduction. The flake-like and needle-like aluminide particles in the as cast microstructure were fragmented and aligned in the aluminium matrix, giving rise to short needle-like particles in parallel rows. These aluminide particles had rough edges which were rounded by heat treatment. The TiB2 particles were not affected in size or morphology by either the rolling or the heat treatment. The grain refining performance of the as cast materials was assessed. It was found that the experimental grain refiners had poorer performance than commercial grain refiners. The influence of mechanical and thermal treatments on the grain refining performance of the experimental Al-Ti-B grain refiners was also assessed. Cold working of the grain refiners had a positive influence on the grain refining performance promoting finer grain. Heat treatment of grain refiners after cold working was deleterious and led to a loss of grain refining capacity. The size and size distribution of TiB2 particles were determined related to grain refining performance and compared to theoretical models. A relationship was established between the size distribution of the TiB2 particles in the grain refiners and the grain size of inoculated aluminium. Grain refinement increased with decreasing proportion of coarse TiB2 particles in the grain refiners. This corresponded to a decrease in Ti and B contents and an increase in the Ti/B ratio.

Thesis advisor: Richard Sweeney / With climate change becoming a global problem more people are paying attention to, a common goal to reduce Greenhouse Gas (GHG) emissions is recognized by most countries. However, usually emission reduction is more difficult to achieve in developing countries because of the lack of advanced emission reduction technology. Thus,one of the important ways to improve emission reduction technology in developing countries is through technology transfer, which is to import more advanced emission reduction technology from developed countries to developing countries. In this study, I explore the level and determinants of technology transfer using data of projects from four sectors under the CDM(Clean Development Mechanism) in China. I find that large scale projects with higher emission reduction amount tend to have higher probability of technology transfer. Also, more economically and technologically advanced provinces tend to have more projects with technology transfer. / Thesis (BA) — Boston College, 2017. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Economics.

Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Shewanella oneidensis is a facultative, gram-negative microbe that, in the absence of oxygen, can use a wide variety of terminal electron acceptors including iron, manganese, uranium, nitrite, nitrate, sulfate, fumarate, and DMSO. The anaerobic versatility is believed to be the result of a highly branched electron transfer pathway involving many redox-active proteins. Shewanella is capable of dissimilatory metal reduction (DMR) of insoluble iron and manganese oxides, in which electrons are transferred from the cell's interior to its exterior. Several multiheme c -type cytochromes comprise a pathway for this electron transfer. These cytochromes, specifically the tetraheme protein, CymA, and the decaheme protein, MtrA, are the primary focus of this thesis. The current model of electron transfer indicates that electrons originate in the cytoplasmic membrane from the menaquinol pool, and are transferred into the periplasm by CymA. From here the pathway branches and electrons are transferred into several potential periplasmic targets, including MtrA. MtrA may then transfer electrons directly or indirectly to MtrC and OmcA, which have been shown to reduce exogenous electron acceptors such as iron oxides. Recently, it has been suggested that MtrA and MtrC dock with 13-barrel protein, MtrB and transfer electrons through the porin sheath. Here, the DMR pathway has been studied with respect to four aims: (1) purification and characterization of the multiheme cytochromes through the use of non-catalytic protein film voltammetry (PFV), (2) structural analysis of MtrA by small angle X-ray scattering (SAXS), (3) investigation of protein-protein interactions via catalytic PFV and anaerobic affinity chromatography, and (4) exploration of heme cofactor function within the tetraheme cytochrome, CymA and MtrA by characterizing heme knockout mutants of the two proteins. We demonstrate that these proteins interact to form an electron transfer pathway from the cytoplasm to terminal electron acceptors on the outside of the cell through a "wire" of heme cofactors. Additionally, the data support the model that MtrA can span a large portion of the peri plasmic space to act as an intermediary by accepting electrons from CymA and subsequently docking with MtrB to transfer electrons to MtrC. / 2031-01-02

Companies developing new products have a wide variety of product development (PD) processes from which to choose. Each process offers a different method of iteration to manage risk. Companies must therefore consider the nature and level of risks they face in order to determine the most appropriate iteration and PD process. This paper identifies principles of risk and iteration inherent in product development and then explains how several different PD processes manage risk through iteration. It explains current research on PD decision criteria and concludes by proposing a framework to help companies better select PD processes. / Singapore-MIT Alliance (SMA)